Former prime minister John Howard has stood by his decision to join the 2003 invasion of Iraq, insisting he and fellow world leaders should not be judged with the benefit of hindsight.

I don't believe that, on the basis of the information that was available to me, it was the wrong decision. I really don't. 

Former prime minister John Howard

Responding to a long-awaited British inquiry report into the Iraq war – which is today widely regarded as a strategic blunder by experts – Mr Howard maintained it was the right thing to do with the information his government had at the time.

Former prime minister John Howard talking about the Chilcot report. Photo: Edwina Pickles

The Chilcot report, based on seven years' work, concluded that the invasion had been launched before the diplomatic options had been exhausted, and was based on flawed intelligence that "should have been" challenged but was not.

It was also critical of the occupation strategy after dictator Saddam Hussein had been toppled. But it did not back claims that intelligence had been doctored to justify the war.

Declaring "there was no lie" about the incorrect intelligence, Mr Howard said although no weapons of mass destruction were ever found, it was clear the Saddam regime wanted to resume its WMD program.

Independent MP Andrew Wilkie has called for Mr Howard to face a war crimes trial over the decision. Photo: Alex Ellinghausen

"Do I apologise for the decision that I took?" Mr Howard said at a news conference in Sydney. "I defend that decision. I don't retreat from it. I don't believe that, on the basis of the information that was available to me, it was the wrong decision. I really don't."

Later on Sky News, Mr Howard refused to acknowledge that the invasion itself had been a mistake, repeatedly insisting that critics were enjoying the benefit of hindsight.

However former Labor leader and Washington ambassador Kim Beazley, who took part in an Australian parliamentary inquiry into the war, said Labor had opposed the invasion because it was clear the Iraq regime had had no involvement in the September 11 terrorist attacks.

"It is quite obvious that that was not the fight that needed to be fought at that time," he said. "The consequences have been widespread and devastating."

Independent MP Andrew Wilkie, who quit as a government intelligence analyst in 2003 over Mr Howard's decision, said the invasion had ultimately allowed the so-called Islamic State to flourish and caused the 2005 Bali bombing and the Lindt Cafe siege. He called for a full Australian inquiry and said Mr Howard should face international war crimes trials.

Mr Howard branded these views "irrational" and "an absurd proposition".

Other commentators stopped short of calling for a further Australian inquiry but said lessons out of Iraq needed to be learnt.

Peter Leahy, who was the chief of army from 2002 to 2008, said Australia needed better public and parliamentary debates about decisions to go to war and a clearer focus on its strategic interests.

"We need to be much more independent, much more conscious of our own national interest, and conscious of who we choose to partner with, because the US don't have a really good record over the last few decades," said Professor Leahy, who now heads the University of Canberra's National Security Institute.

James Brown, a former Army officer who served in Iraq and now is based at the US Studies Centre in Sydney, similarly said Australia had made too little effort to learn from the mistakes after the 2003 invasion.

"This really points out by contrast that Australia's debate on Iraq is frozen in the politics of 2003 and is still focused on apportioning blame rather than better equipping us to make future decisions on military action," he said.

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